Abstract : The management of vast forested zones contaminated by radiocesium (rCs) following the Chernobyl and
Fukushima fallout is of great social and economic concern in affected areas and requires appropriate dynamic
models as predictive or questioning tools. Generally, the existing radio-ecological models need less fragmented
data and more ecological realism in their quantitative description of the rCs cycling processes. The model TRIPS
(“Transfer of Radionuclide In Perennial vegetation Systems”) developed in this study privileged an integrated
approach which makes the best use of mass balance studies and available explicit experimental data for Scots
pine stands. A main challenge was the differentiation and calibration of foliar absorption as well as root uptake
in order to well represent the rCs biocycling. The general dynamics of rCs partitioning was simulated with a
relatively good precision against an independent series of observed values. In our scenario the rCs biological
cycling enters a steady-state about 15 years after the atmospheric deposits. At that time, the simulations showed
an equivalent contribution of foliage and root uptake to the tree contamination. But the root uptake seems not
sufficient to compensate the activity decline in the tree. The initial foliar uptake and subsequent internal
transfers were confirmed to have a great possible impact on the phasing of tree contamination. An extra finding
concerns the roots system acting as a buffer in the early period. The TRIPS model is particularly useful in cases
where site-specific integrated datasets are available, but it could also be used with adequate caution to generic
sites. This development paves the way for simplification or integration of new modules, as well as for a larger
number of other applications for the Chernobyl or Fukushima forests once the appropriate data become available.
According to the sensitivity analysis that involves in particular reliable estimates of net foliar uptake as well
as root uptake not disconnected from rCs exchange reactions in soil.